Merge pull request #12296 from anuragkumawat/JAVA-12383

JAVA-12383 GitHub Issue: Incorrect results in Kadane Algorithm for Maximal Subarray

algorithms-modules/algorithms-miscellaneous-5/src/main/java/com/baeldung/algorithms/maximumsubarray/KadaneAlgorithm.java

@@ -14,7 +14,7 @@ public class KadaneAlgorithm {
         int end = 0;
 
         int maxSoFar = arr[0], maxEndingHere = arr[0];
-        for (int i = 0; i < size; i++) {
+        for (int i = 1; i < size; i++) {
 
             if (arr[i] > maxEndingHere + arr[i]) {
                 start = i;

algorithms-modules/algorithms-miscellaneous-5/src/test/java/com/baeldung/algorithms/maximumsubarray/KadaneAlgorithmUnitTest.java

@@ -27,4 +27,16 @@ class KadaneAlgorithmUnitTest {
         //then
         assertEquals(-1, maxSum);
     }
+    
+    @Test
+    void givenArrayWithAllPosiitveNumbersWhenMaximumSubarrayThenReturnsExpectedResult() {
+        //given
+        int[] arr = new int[] {4, 1, 3, 2};
+        //when
+        KadaneAlgorithm algorithm = new KadaneAlgorithm();
+        int maxSum = algorithm.maxSubArraySum(arr);
+        //then
+        assertEquals(10, maxSum);
+    }
+
 }